A variety of different types of sensors are being used in portable and mobile devices. These sensors extend beyond microphones and radio receivers to accelerometers, gyroscopes, compasses, altimeters, barometers and more. For some special purpose-built devices biometric or environmental sensors are used for medical or scientific purposes.
As miniaturization advances, there are efforts to construct sensors within smaller packages. In some cases, a sensor or a suite of sensors may be packaged together in a manner similar to an integrated circuit chip package. In other cases, sensors are combined with integrated circuits in a single package.
Some types of sensors, such as accelerometers and gyroscopes may require a permanent magnet, depending on the particular design of the sensor. The particular placement of the magnet will depend upon the design of the package.